Chrisbequick

They don't? I guess my old setup with Mac shorties going 112 through the traps on a stock tune, stock heads, stock shortbock, and a little cam was defying the laws of physics. I guess the LS1 cam-only TA that we built that put down 401 at the wheels through Mac shorties and the stock cat-back never actually happened. I guess all the shorty headers I've installed over the years in my career on all the various makes and models of cars that showed a gain must have been from a fluke of the dyno. I should probably remove the shorty headers from my home-built turbo system that makes over 700 hp at the flywheel and replace them with cast-iron manifolds since they aren't helping at all.

Seriously. Where do you people get this info?

-Chris

Myxtreme1

BlkLT1Z28

Thats just what some people say that are jealous and dont have LT's or cant have them b/c of there state........j/k

I think he meant that may not be helping with his combo, they will hold you back eventually. And the biggest restriction in a turbo system is the turbo, and I bet that if you had LT's........you'd have 600rwhp! no, j/k again.

Alvin@pcmforless.com

Have you tried talking to bryan at pcmforless about diagnosing whats wrong?

1-bad-z28

you have said the answer several times. Your plugs are white, you have a intake backfire, and you have ls1 28# injectors set at 43psi fuel pressure giving you 24# injectors. That sucka is running lean killing power. You may have other problems as well but i would definetly fattin up the fuel first then work on the other stuff. Those 36#ers will definetly help you even with the 28# tune. I would get to a dyno asap to get it dialed in.

Alvin@pcmforless.com

It could be anything at this point like a dirty maf or leaking behind the maf.

I personally stay away from the MAF cars, but I've seen Bryan on the dyno make a totally stock pull on a MAF car have it come out totally lean or something then he either cleans it or finds the leak makes anthor pull and the car runs right where it supposed to.

Also, those LS1 injectors can often be misleading. They could be out of a truck, or any year LS1 (which flow different also).

izzyz28

I wouldn't trust 1/8 mi. E.T at all if you're trying to quantify power gains. Maybe MPH, but definately not E.T. I was consistently running 8.80's @ 82 MPH N/A spinning a little this past Saturday. With a ~100 shot I ran a 9.20 @ 88.5 MPH, spinning to half track. Shoot, my best N/A run is in sig, and my best N2O run is an 8.50 @ 88 MPH. So I picked up a few MPH and only a couple hundredths of a second. On street tires E.T.'s don't mean jack.

WS Sick

The thing is most definately running lean, get the 36ers inthere and change the injector flow rate, set the fuel pressure at 43 and then datalog again, If you have a laptop buy yourself a ALDL connector cable and dowload Datamaster for free and log.

brain

Why do the shorty header tools come out in such force when a simple comment is made? I didn't say that they were hurting the performance, I didn't say that was the only problem. Thats fantastic that you ran 112 with shortys, makes me think you would have run at least 115 with LTs. Thats great that an LS1 made 401 with shortys, probably would have made 425 or more with LTs. Plus, headers for a turbo are a whole different animal, but I'm sure you knew that since you have a 700 hp beast, lol.

Dannysz28

Well i bought some used 36lb injectors and had my pcm tuned for them. After installing them i went for a test run and after i got down the road the car started missing and when i put it in park and raced the engine, it started poping and backfiring. When you hold the rpm about 2000rpm, it starts missing and poping and the tack start to jump a little. Do you guys think a clogged injector would make it do that?

MachinistOne

Sounds ignition related. Those stock heads are seriously hurting power, but the popping is most likely spark scatter or lash adjustment. Incorrect ignition timing advance.